EUV multilayer coatings for the Atmospheric Imaging Assembly instrument aboard the Solar Dynamics Observatory (open access)

EUV multilayer coatings for the Atmospheric Imaging Assembly instrument aboard the Solar Dynamics Observatory

Multilayer coatings for the 7 EUV channels of the AIA have been developed and completed successfully on all AIA flight mirrors. Mo/Si coatings (131, 171, 193.5, 211 {angstrom}) were deposited at Lawrence Livermore National Laboratory (LLNL). Mg/SiC (304, 335 {angstrom}) and Mo/Y (94 {angstrom}) coatings were deposited at Columbia University. EUV reflectance of the 131/335 {angstrom}, 171 {angstrom}, 193.5/211 {angstrom} primary and secondary flight mirrors and the 94/304 {angstrom} secondary flight mirror was measured at beamline 6.3.2. of the Advanced Light Source (ALS) at LBNL. EUV reflectance of the 94/304 {angstrom} primary and secondary flight mirrors was measured at beamline X24C of the National Synchrotron Light Source (NSLS) at Brookhaven National Lab. Preliminary EUV reflectance measurements of the 94, 304 and 335 {angstrom} coatings were performed with a laser plasma source reflectometer located at Columbia University. Prior to multilayer coating, Atomic Force Microscopy (AFM) characterization and cleaning of all flight substrates was performed at LLNL.
Date: February 9, 2006
Creator: Soufli, R.; Windt, D. L.; Robinson, J. C.; Baker, S. L.; Spiller, E.; Dollar, F. J. et al.
System: The UNT Digital Library
Neutron and Photon Transport in Sea-Going Cargo Containers (open access)

Neutron and Photon Transport in Sea-Going Cargo Containers

Factors affecting sensing of small quantities of fissionable material in large sea-going cargo containers by neutron interrogation and detection of {beta}-delayed photons are explored. The propagation of variable-energy neutrons in cargos, subsequent fission of hidden nuclear material and production of the {beta}-delayed photons, and the propagation of these photons to an external detector are considered explicitly. Detailed results of Monte Carlo simulations of these stages in representative cargos are presented. Analytical models are developed both as a basis for a quantitative understanding of the interrogation process and as a tool to allow ready extrapolation of the results to cases not specifically considered here.
Date: February 9, 2005
Creator: Pruet, J; Descalle, M; Hall, J; Pohl, B & Prussin, S G
System: The UNT Digital Library
FUEL CASK IMPACT LIMITER VULNERABILITIES (open access)

FUEL CASK IMPACT LIMITER VULNERABILITIES

Cylindrical fuel casks often have impact limiters surrounding just the ends of the cask shaft in a typical 'dumbbell' arrangement. The primary purpose of these impact limiters is to absorb energy to reduce loads on the cask structure during impacts associated with a severe accident. Impact limiters are also credited in many packages with protecting closure seals and maintaining lower peak temperatures during fire events. For this credit to be taken in safety analyses, the impact limiter attachment system must be shown to retain the impact limiter following Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC) impacts. Large casks are often certified by analysis only because of the costs associated with testing. Therefore, some cask impact limiter attachment systems have not been tested in real impacts. A recent structural analysis of the T-3 Spent Fuel Containment Cask found problems with the design of the impact limiter attachment system. Assumptions in the original Safety Analysis for Packaging (SARP) concerning the loading in the attachment bolts were found to be inaccurate in certain drop orientations. This paper documents the lessons learned and their applicability to impact limiter attachment system designs.
Date: February 9, 2009
Creator: Leduc, D; Jeffery England, J & Roy Rothermel, R
System: The UNT Digital Library
Quark Matter 2006: High-pt and jets (open access)

Quark Matter 2006: High-pt and jets

An overview of new experimental results on high-pT particleproduction and jets in heavy ion collisions from the Quark Matter 2006conference is presented.
Date: February 9, 2007
Creator: van Leeuwen, Marco
System: The UNT Digital Library
Three-Dimensional Hydrodynamic Experiments on the National Ignition Facility (open access)

Three-Dimensional Hydrodynamic Experiments on the National Ignition Facility

The production of supersonic jets of material via the interaction of a strong shock wave with a spatially localized density perturbation is a common feature of inertial confinement fusion and astrophysics. The behavior of two-dimensional (2D) supersonic jets has previously been investigated in detail [J. M. Foster et. al, Phys. Plasmas 9, 2251 (2002)]. In three-dimensions (3D), however, there are new aspects to the behavior of supersonic jets in compressible media. In this paper, the commissioning activities on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)] to enable hydrodynamic experiments will be presented as well as the results from the first series of hydrodynamic experiments. In these experiments, two of the first four beams of NIF are used to drive a 40 Mbar shock wave into millimeter scale aluminum targets backed by 100 mg/cc carbon aerogel foam. The remaining beams are delayed in time and are used to provide a point-projection x-ray backlighter source for diagnosing the three-dimensional structure of the jet evolution resulting from a variety of 2D and 3D features. Comparisons between data and simulations using several codes will be presented.
Date: February 9, 2005
Creator: Blue, B E; Robey, H F; Glendinning, S G; Bono, M J; Dixit, S N; Foster, J M et al.
System: The UNT Digital Library
Amorphous clusters in Co implanted ZnO induced by boron pre-implantation (open access)

Amorphous clusters in Co implanted ZnO induced by boron pre-implantation

We demonstrate the formation of superparamagnetic/ferromagnetic regions within ZnO(0001) single crystals sequently implanted with B and Co. While the pre-implantation with B plays a minor role for the electrical transport properties, its presence leads to the formation of amorphous phases. Moreover, B acts strongly reducing on the implanted Co. Thus, the origin of the ferromagnetic ordering in local clusters with large Co concentration is itinerant d-electrons as in the case of metallic Co. The metallic amorphous phases are non-detectable by common X-ray diffraction.
Date: February 9, 2009
Creator: Potzger, K.; Shalimov, A.; Zhou, S.; Schmidt, H.; Mucklich, A.; Helm, M. et al.
System: The UNT Digital Library
Indications of Conical Emission of Charged Hadrons at the BNL Relativistic HeavyIon Collider (open access)

Indications of Conical Emission of Charged Hadrons at the BNL Relativistic HeavyIon Collider

Three-particle azimuthal correlation measurements with a high transverse momentum trigger particle are reported for pp, d + Au, and Au + Au collisions at {radical}s{sub NN} = 200 GeV by the STAR experiment. Dijet structures are observed in pp, d + Au and peripheral Au + Au collisions. An additional structure is observed in central Au + Au data, signaling conical emission of correlated charged hadrons. The conical emission angle is found to be {theta} = 1.37 {+-} 0.02(stat){sub -0.07}{sup +0.06}(syst), independent of p{sub {perpendicular}}.
Date: February 9, 2009
Creator: STAR Collaboration
System: The UNT Digital Library
Spin Equilibria in Monomeric Manganocenes: Solid State Magnetic and EXAFS Studies (open access)

Spin Equilibria in Monomeric Manganocenes: Solid State Magnetic and EXAFS Studies

Magnetic susceptibility measurements and X-ray data confirm that tert-butyl-substituted manganocenes [(Me{sub 3}C){sub n}C{sub 5}H{sub 5?n}]{sub 2}Mn (n = 1, 2) follow the trend previously observed with the methylated manganocenes; that is, electron-donating groups attached to the Cp ring stabilize the low-spin (LS) electronic ground state relative to Cp{sub 2}Mn and exhibit higher spin-crossover (SCO) temperatures. However, introducing three CMe{sub 3} groups on each ring gives a temperature-invariant high-spin (HS) state manganocene. The origin of the high-spin state in [1,2,4-(Me{sub 3}C){sub 3}C{sub 5}H{sub 2}]{sub 2}Mn is due to the significant bulk of the [1,2,4-(Me{sub 3}C){sub 3}C{sub 5}H{sub 2}]{sup -} ligand, which is sufficient to generate severe inter-ring steric strain that prevents the realization of the low-spin state. Interestingly, the spin transition in [1,3-(Me{sub 3}C){sub 2}C{sub 5}H{sub 3}]{sub 2}Mn is accompanied by a phase transition resulting in a significant irreversible hysteresis ({Delta}T{sub c} = 16 K). This structural transition was also observed by extended X-ray absorption fine-structure (EXAFS) measurements. Magnetic susceptibility studies and X-ray diffraction data on SiMe{sub 3}-substituted manganocenes [(Me{sub 3}Si){sub n}C{sub 5}H{sub 5-n}]{sub 2}Mn (n = 1, 2, 3) show high-spin configurations in these cases. Although tetra- and hexasubstituted manganocenes are high-spin at all accessible temperatures, the disubstituted manganocenes exhibit …
Date: February 9, 2009
Creator: Walter, M. D.; Sofield, C. D.; Booth, C. H. & Andersen, R. A.
System: The UNT Digital Library
Annual Growth Bands in Hymenaea courbaril (open access)

Annual Growth Bands in Hymenaea courbaril

One significant source of annual temperature and precipitation data arises from the regular annual secondary growth rings of trees. Several tropical tree species are observed to form regular growth bands that may or may not form annually. Such growth was observed in one stem disk of the tropical legume Hymenaea courbaril near the area of David, Panama. In comparison to annual reference {Delta}{sup 14}C values from wood and air, the {Delta}{sup 14}C values from the secondary growth rings formed by H. courbaril were determined to be annual in nature in this one stem disk specimen. During this study, H. courbaril was also observed to translocate recently produced photosynthate into older growth rings as sapwood is converted to heartwood. This process alters the overall {Delta}{sup 14}C values of these transitional growth rings as cellulose with a higher {Delta}{sup 14}C content is translocated into growth rings with a relatively lower {Delta}{sup 14}C content. Once the annual nature of these growth rings is established, further stable isotope analyses on H. courbaril material in other studies may help to complete gaps in the understanding of short and of long term global climate patterns.
Date: February 9, 2004
Creator: Westbrook, J. A.; Guilderson, T. P. & Colinvaux, P. A.
System: The UNT Digital Library
The Effect of Diluent Gases In The Shock Tube and Rapid Compression Machine (open access)

The Effect of Diluent Gases In The Shock Tube and Rapid Compression Machine

Studying the details of hydrocarbon chemistry in an internal combustion engine is not straightforward. A number of factors, including varying conditions of temperature and pressure, complex fluid motions, as well as variation in the composition of gasoline, render a meaningful characterization of the combusting system difficult. Some simplified experimental laboratory devices offer an alternative to complex engine environments: they remove some of the complexities that exist in real engines but retain the ability to work under engine-relevant conditions. The choice of simplified experimental devices is limited by the range of temperature and pressure at which they can operate; only the shock tube and rapid compression machine (RCM) can reach engine-relevant temperatures and pressures quickly enough and yet withstand the high pressures that occur after the ignition event. Both devices, however, suffer a common drawback: the use of inert diluent gases has been shown to affect the measured ignition delay time under some experimental conditions. Interestingly, this effect appears to be opposite in the shock tube and RCM: in the comparative study of the carrier gases argon and nitrogen, argon decreases the ignition delay time in the shock tube, but increases it in the RCM. This observation is investigated in more …
Date: February 9, 2007
Creator: Silke, E; W?rmel, J; O?Conaire, M; Simmie, J & Curran, H
System: The UNT Digital Library
Charm and Charmonium Spectroscopy From B-Factories (open access)

Charm and Charmonium Spectroscopy From B-Factories

New and recent results are presented on charm and charmonium spectroscopy from BABAR experiment at SLAC. In particular, measurements on D{sub sJ} states branching fractions have been performed both in B-decays and inclusive e{sup +}e{sup -} {yields} c{bar c} interactions. Here a search for D{sub sj}(2632) has been performed and a new D{sub sJ} state at a mass of 2.856 GeV/c{sup 2} has been observed. A search for Y(4260) has been performed in exclusive D{sub D} production from initial-state radiation.
Date: February 9, 2007
Creator: Palano, Antimo
System: The UNT Digital Library
Nucleation and growth of the Alpha-Prime Phase martensitic phase in Pu-Ga Alloys (open access)

Nucleation and growth of the Alpha-Prime Phase martensitic phase in Pu-Ga Alloys

In a Pu-2.0 at% Ga alloy, it is observed experimentally that the amount of the martensitic alpha-prime product formed upon cooling the metastable delta phase below the martensite burst temperature (M{sub b}) is a function of the holding temperature and holding time of a prior conditioning (''annealing'') treatment. Before subjecting a sample to a cooling and heating cycle to form and revert the alpha-prime phase, it was first homogenized for 8 hours at 375 C to remove any microstructural memory of prior transformations. Subsequently, conditioning was carried out in a differential scanning calorimeter apparatus at temperatures in the range between -50 C and 370 C for periods of up to 70 hours to determine the holding time and temperature that produced the largest volume fraction of alpha-prime upon subsequent cooling. Using transformation peak areas (i.e., the heats of transformation) as a measure of the amount of alpha-prime formed, the largest amount of alpha-prime was obtained following holding at 25 C for at prime least 6 hours. Additional time at 25 C, up to 70 hours, did not increase the amount of subsequent alpha-prime formation. At 25 C, the Pu-2.0 at% Ga alloy is below the eutectoid transformation temperature in the …
Date: February 9, 2005
Creator: Blobaum, K M; Krenn, C R; Wall, M A; Massalski, T B & Schwartz, A J
System: The UNT Digital Library
Use of TOUGHREACT to Simulate Effects of Fluid Chemistry onInjectivity in Fractured Geothermal Reservoirs with High Ionic StrengthFluids (open access)

Use of TOUGHREACT to Simulate Effects of Fluid Chemistry onInjectivity in Fractured Geothermal Reservoirs with High Ionic StrengthFluids

Recent studies suggest that mineral dissolution/precipitation and clay swelling effects could have a major impact on the performance of hot dry rock (HDR) and hot fractured rock (HFR) reservoirs. A major concern is achieving and maintaining adequate injectivity, while avoiding the development of preferential short-circuiting flow paths. A Pitzer ionic interaction model has been introduced into the publicly available TOUGHREACT code for solving non-isothermal multi-phase reactive geochemical transport problems under conditions of high ionic strength, expected in typical HDR and HFR systems. To explore chemically-induced effects of fluid circulation in these systems, we examine ways in which the chemical composition of reinjected waters can be modified to improve reservoir performance. We performed a number of coupled thermo-hydrologic-chemical simulations in which the fractured medium was represented by a one-dimensional MINC model (multiple interacting continua). Results obtained with the Pitzer activity coefficient model were compared with those using an extended Debye-Hueckel equation. Our simulations show that non-ideal activity effects can be significant even at modest ionic strength, and can have major impacts on permeability evolution in injection-production systems. Alteration of injection water chemistry, for example by dilution with fresh water, can greatly alter precipitation and dissolution effects, and can offer a powerful …
Date: February 9, 2005
Creator: Xu, Tianfu; Zhang, Guoxiang & Pruess, Karsten
System: The UNT Digital Library
A Parallel Finite-Difference Approach for Three-Dimensional Transient Electromagnetic Modeling With Galvanic Sources (open access)

A Parallel Finite-Difference Approach for Three-Dimensional Transient Electromagnetic Modeling With Galvanic Sources

None
Date: February 9, 2004
Creator: Commer, Michael & Newman, Gregory
System: The UNT Digital Library
Theoretical investigations of I = 5/2 quadrupolar spin dynamics in the sudden-passage regime (open access)

Theoretical investigations of I = 5/2 quadrupolar spin dynamics in the sudden-passage regime

None
Date: February 9, 2002
Creator: Walls, Jamie D.; Lim, Kwang Hun; Logan, John W.; Urban, Jeffry T.; Jerschow, Alexej & Pines, Alexander
System: The UNT Digital Library
Actinide Thermodynamics at Higher Temperatures (open access)

Actinide Thermodynamics at Higher Temperatures

This report is about the Actinide Thermodynamics at Higher Temperatures
Date: February 9, 2005
Creator: Friese, J.
System: The UNT Digital Library
The Axion Mass in Modular Invariant Supergravity (open access)

The Axion Mass in Modular Invariant Supergravity

When supersymmetry is broken by condensates with a single condensing gauge group, there is a nonanomalous R-symmetry that prevents the universal axion from acquiring a mass. It has been argued that, in the context of supergravity, higher dimension operators will break this symmetry and may generate an axion mass too large to allow the identification of the universal axion with the QCD axion. We show that such contributions to the axion mass are highly suppressed in a class of models where the effective Lagrangian for gaugino and matter condensation respects modular invariance (T-duality).
Date: February 9, 2005
Creator: Butter, Daniel & Gaillard, Mary K.
System: The UNT Digital Library
Compact Optical Technique for Streak Camera Calibration (open access)

Compact Optical Technique for Streak Camera Calibration

None
Date: February 9, 2004
Creator: Bell, Perry; Griffith, Roger; Hagans, Karla; Lerche, Richard; Allen, Curt; Davies, Terence et al.
System: The UNT Digital Library
Incipient Plasticity during Nanoindentation at Elevated Temperatures (open access)

Incipient Plasticity during Nanoindentation at Elevated Temperatures

The onset of plastic deformation during nanoindentation is studied, focusing upon the effects of temperature variation. By performing indentations on pure (100)-oriented platinum at room temperature, 100 and 200 C, we demonstrate that higher temperatures promote the discretization of plasticity into sharp bursts of activity. Additionally, the transition from elastic to plastic deformation occurs at progressively lower stress levels as temperature is increased. These results are in line with expectations for stress-biased, thermally-activated deformation processes such as the nucleation of dislocations or the abrupt release of dislocation entanglements.
Date: February 9, 2004
Creator: Lund, A C; Hodge, A M & Schuh, C
System: The UNT Digital Library
On the Violence of High Explosive Reactions (open access)

On the Violence of High Explosive Reactions

High explosive reactions can be caused by three general energy deposition processes: impact ignition by frictional and/or shear heating; bulk thermal heating; and shock compression. The violence of the subsequent reaction varies from benign slow combustion to catastrophic detonation of the entire charge. The degree of violence depends on many variables, including the rate of energy delivery, the physical and chemical properties of the explosive, and the strength of the confinement surrounding the explosive charge. The current state of experimental and computer modeling research on the violence of impact, thermal, and shock-induced reactions is reviewed.
Date: February 9, 2004
Creator: Tarver, C M & Chidester, S K
System: The UNT Digital Library
Building Biochips: A Protein Production Pipeline (open access)

Building Biochips: A Protein Production Pipeline

Protein arrays are emerging as a practical format in which to study proteins in high-throughput using many of the same techniques as that of the DNA microarray. The key advantage to array-based methods for protein study is the potential for parallel analysis of thousands of samples in an automated, high-throughput fashion. Building protein arrays capable of this analysis capacity requires a robust expression and purification system capable of generating hundreds to thousands of purified recombinant proteins. We have developed a method to utilize LLNL-I.M.A.G.E. cDNAs to generate recombinant protein libraries using a baculovirus-insect cell expression system. We have used this strategy to produce proteins for analysis of protein/DNA and protein/protein interactions using protein microarrays in order to understand the complex interactions of proteins involved in homologous recombination and DNA repair. Using protein array techniques, a novel interaction between the DNA repair protein, Rad51B, and histones has been identified.
Date: February 9, 2004
Creator: de Carvalho-Kavanagh, M & Albala, J S
System: The UNT Digital Library
End-Pumped 895 nm Cs Laser (open access)

End-Pumped 895 nm Cs Laser

A scientific demonstration of a Cs laser is described in which the measured slope efficiency is as high as 0.59 W/W using a Ti:Sapphire laser as a surrogate diode-pump. In addition to presenting experimental data, a laser energetics model that accurately predicts laser performance is described and used to model a power-scaled, diode-pumped system.
Date: February 9, 2004
Creator: Beach, R J; Krupke, W F; Kanz, V K; Payne, S A; Dubinskii, M A & Merkle, L D
System: The UNT Digital Library
Solubility of Lamotrigine, Diazepam, Clonazepam, and Phenobarbital in Propylene Glycol + Water Mixtures at 298.15 K (open access)

Solubility of Lamotrigine, Diazepam, Clonazepam, and Phenobarbital in Propylene Glycol + Water Mixtures at 298.15 K

Article discussing the solubility of lamotrigine, diazepam, clonazepam, and phenobarbital in propylene glycol + water mixtures at 298.15 K.
Date: February 9, 2009
Creator: Shayanfar, Ali; Acree, William E. (William Eugene) & Jouyban, Abolghasem
System: The UNT Digital Library
Dynamic pathways for viral capsid assembly (open access)

Dynamic pathways for viral capsid assembly

We develop a class of models with which we simulate the assembly of particles into T1 capsid-like objects using Newtonian dynamics. By simulating assembly for many different values of system parameters, we vary the forces that drive assembly. For some ranges of parameters, assembly is facile, while for others, assembly is dynamically frustrated by kinetic traps corresponding to malformed or incompletely formed capsids. Our simulations sample many independent trajectories at various capsomer concentrations, allowing for statistically meaningful conclusions. Depending on subunit (i.e., capsomer) geometries, successful assembly proceeds by several mechanisms involving binding of intermediates of various sizes. We discuss the relationship between these mechanisms and experimental evaluations of capsid assembly processes.
Date: February 9, 2006
Creator: Hagan, Michael F. & Chandler, David
System: The UNT Digital Library